The present invention relates generally to respirator facepieces and, more particularly, to full facepieces for use in environments in which toxic substances may be present.
A full facepiece, air-purifying respirator typically includes a face mask and a head harness for securing the face mask to the user. See, for example, U.S. Pat. No. 5,924,420. The face mask, which is sealed to the face of the user, typically includes a lens through which the user can view the surrounding environment. The face mask also includes one or more inhalation ports in fluid connection with one or more filtering elements (for example, chemical and particulate filtering canisters or cartridges) through which inspired air passes into the face mask and an exhalation port through with expired air passes out of the mask.
A nose cup is typically provided around the nose and mouth area of the user to assist in directing the flow of air into and out of the face mask. The nose cup, for example, assists in directing expired air to the exhalation port, reducing buildup of carbon dioxide and in preventing expired air, which is rich in moisture, from causing “fogging” of the face mask lens. In currently available respirators, the nose cup includes one or more check valves that allow inspired air to enter the nose cup, but prevent expired air from passing through the nose cup to contact the lens. Such valves can complicate the manufacture, assembly and maintenance of the respirator.
One or more air filters, such as filtering canisters, filtering cartridges or other filtering elements are typically removably attachable (for example, via threading or via a bayonet-type connection) to connectors or interfaces attached to the face mask as part of the inhalation port(s) of the face mask. In a number of current face masks, multi-component filter element connectors are manufactured separately from the remainder of the face mask and later attached to the face mask via, for example, cooperating threaded attachment members. Filter element connectors can also be attached to the face mask via an adhesive or via a polymeric welding bond. In general, the manner in which the filter element connectors are currently attached to face masks complicates manufacturing, assembly and maintenance of such face masks.
It is therefore, desirable to develop face masks and components therefor which reduce and, preferably, eliminate the above-identified and other problems with currently available face masks.